Many will say tape is a no no. So if you do this do so at your own risk. Personally If I have heavy hides, I place the probes in the hide, being help down by the hide. All my snakes except the BP burrow and do not have heavy hides. I too use foil tape on some cages, but prefer aquarium sealant when possible. Tape would bad should it ever stick to a snake.
Having used foil tape in the field (work), I personal feel safe with the small pieces I have applied to a clean glass surface and completely affixed it making sure to have no air bubbles. Every thorough cleaning I add new tape. I have never even had a small end pulled up in two years.
Again aquarium sealant is safer and non-toxic, just takes a while to cure. Tape can be risky so USE AT YOUR OWN RISK.